Several manufacturers of MRI systems currently try to develop pure cordless/wireless MRI coils. A prerequisite for such wireless MRI coils is that an analog magnetic resonance (MR) signal (in the case of an analog coil) or acquired MR data (in the case of a digital coil) can be transported to a MR examination system via a high-speed wireless communication link.
A wireless communication link has a certain quality of service (QoS) with respect to latency and bandwidth properties of such a link. In real life, a performance of a wireless data transport depends to a large extent on an actual transfer response of a wireless channel used to perform the data transport. The actual transfer response can vary largely in a relatively small time due to e.g. movements of antennas caused for instance by a patient movement. An antenna movement can lead to reflections or absorptions in the radio frequency (RF) domain that may impact a momentary signal-to-noise ratio (SNR) of the wireless channel. This can degrade the communication link at least temporary. In addition, noise from other (or own) equipment may temporarily degrade the communication link as well.
If a number of MRI coil elements/channels increases, a required MR data rate also increases. It is a precondition for an effective usage of wireless MRI systems that the required MR data rate and also a required wireless transport power dissipation can be achieved. In view of the currently available wireless technologies, it may be expected that at least during the next 5 to 10 years these technologies will be a blocking factor for the number of channels that can be sensibly placed in or associated with a MRI coil.
When the actual transport technology is the blocking factor, it would be advantageous to at least get the most out of an available (varying) bandwidth and latency. This can be achieved by a MR-signal-aware lossless compression, but also by compressions with limited loss. However, this may still not suffice to achieve a smooth operation of a wireless MRI system. Acquired MR data should leave the MRI coil as soon as possible after acquiring it, since storing the MR data would require huge amounts of power-dissipating and volume-consuming memory at the MRI coil. Further, with the currently available wireless technologies a performance of the communication link can drop below a certain minimum threshold at some points in time, after which the acquired MR data are simply lost. This is not acceptable from a MRI perspective. It may even be necessary to abort a MRI scan.
When using a wireless MRI coil, another issue to be resolved is to enable a robust wireless control of a MR receiver at the MRI coil with respect to its settings over time. That is, to ensure that control information can be reliably transmitted to the MR receiver is an issue to be resolved.